feat: add comprehensive test suite and CI pipeline

- Add 402 unit tests with 61.7% code coverage
- Add Vitest configuration with coverage reporting
- Extract testable utility functions from services
- Create test.yml workflow (runs on PR and push to main)
- Update docker-build.yml to require tests before building
- Add scheduler-utils.ts and server-config.ts for testable code

Test files added:
- auth.test.ts, medications.test.ts, planner.test.ts
- settings.test.ts, doses.test.ts, share.test.ts
- database.test.ts, server.test.ts, services.test.ts
- env.test.ts, translations.test.ts, integration.test.ts
- e2e-routes.test.ts, stock-calculation.test.ts

backend/package.json

@@ -7,7 +7,10 @@
     "dev": "tsx watch src/index.ts",
     "build": "tsc -p tsconfig.json",
     "start": "node dist/index.js",
-    "migrate": "tsx src/db/migrate.ts"
+    "migrate": "tsx src/db/migrate.ts",
+    "test": "vitest",
+    "test:run": "vitest run",
+    "test:coverage": "vitest run --coverage"
   },
   "dependencies": {
     "@fastify/cookie": "^10.0.1",
@@ -30,7 +33,11 @@
   "devDependencies": {
     "@types/node": "^22.7.4",
     "@types/nodemailer": "^6.4.21",
+    "@types/supertest": "^6.0.2",
+    "@vitest/coverage-v8": "^2.1.9",
+    "supertest": "^7.0.0",
     "tsx": "^4.19.0",
-    "typescript": "^5.5.4"
+    "typescript": "^5.5.4",
+    "vitest": "^2.1.8"
   }
 }